package demo2;

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        //当成10进制来看
        Scanner in = new Scanner(System.in);
        int num = in.nextInt();
        StringBuilder str = new StringBuilder();
        while(num > 0) {
            num--;
            char ch = (char)(num % 26 + 'A');
            str.append(ch);
            num /= 26;
        }
        //反向打印
        for(int i = str.length() - 1; i >= 0; i--) {
            System.out.print(str.charAt(i));
        }
    }
}
